A cover assembly for an open top railcar, the assembly having semi-rigid cover reversibly movable between a closed position atop the railcar and an open position alongside the railcar or separate from it. The cover may be connected to the railcar with hinge-latches or linkage arms which permit the cover to be held flat alongside the railcar in an open position, or removed from the railcar during loading and unloading. A load grooming device shapes the load of a loaded railcar to a selected contour. Opening and closing of covers may be continuous and automated, using curved tracks, cranes or mechanical arms to engage and open covers, and conveying devices or vehicles to handle covers during loading and unloading of railcars.